The electronics industry continues to develop smaller and more powerful equipment that performs many functions which, in turn, require more power. In many cases, auxiliary devices that perform one or more additional functions are associated with such equipment. The auxiliary devices also draw power to perform their intended functions and may require a different voltage than the equipment with which they are associated. Consequently, to provide the power to the main and auxiliary components (sometimes with two or more voltage ranges), two separate power supplies are often employed. More specifically, a main power supply powers the main components and an auxiliary power supply powers the auxiliary components.
While the auxiliary power supply provides a viable solution to power auxiliary devices associated with electronic equipment, there are several drawbacks to such an approach. An additional power supply adds complexity to the electronic equipment in connection with, for instance, the added wiring and circuitry. Of course, any time an additional component is added to electronic equipment, provision must be made to accommodate the larger volume of space associated with the additional component and the increased component cost. In addition, the excess heat generated by the additional power supply can reduce the overall efficiency and reliability of the electronic equipment. In short, adding an auxiliary power supply to electronic equipment generally runs afoul of the industry goal of producing smaller and more efficient electronic systems.
The telecommunications industry is but one environment whereby the power requirements for electronic equipment, such as voice processors and switching equipment, are becoming more demanding. The electronic system frequently consists of several circuit boards housed in a common cabinet. A single board mounted power module (BMPM) often is employed to power all of the equipment in the cabinet.
As a general rule, a smaller BMPM is desirable to use less cabinet space and to allow for a more compact and smaller power supply. Although a smaller BMPM is desirable, more powerful BMPMs are also necessary to supply power to a large number of components. BMPM performance is generally evaluated according to its power density, which is the ratio of the total power output to the total volume of the BMPM. The highest power density (i.e., the smallest volume with the largest possible power output) attainable is the goal. As a practical matter, however, the power density is limited because, as the power output increases additional heat is generated thereby detracting from the efficiency of the power supply. The excess heat also reduces the reliability of the power supply caused by premature component failures. For instance, for every 10.degree. C. increase in operating temperature for the power supply, the mean time between failures generally decreases by a factor of two. With the use of more powerful BMPMs, a concurrent need exists to remove the additional heat generated therefrom.
Presently, finned heat sinks are used with the power supplies to dissipate the heat generated by the BMPMs. Conventional finned heat sinks with external air flow, however, cannot remove enough heat to allow a significant increase in the power density of the BMPMs. To achieve additional heat dissipation, a larger heat sink may be employed, but the larger heat sink effectively lowers the power density of the BMPMs.
In many computer applications, a heat sink and fan assembly are employed to significantly increase heat dissipation capability associated with the power supply. Other active cooling or heat dissipation methods are also available, but provisions must be made to accommodate the additional power to operate the active cooling equipment. The active cooling or heat dissipation equipment is particularly attractive in the telecommunications industry, if the costs and complexity associated with such designs can be managed.
Accordingly, what are needed in the art is a system and method of providing power to auxiliary components, such as active cooling devices, without appreciably adding to the overall complexity of the electronic equipment.